Making a Dichotomous Key with several
Biochemical Results to solve for Gram Negative ‘Unknown’ Bacteria
Introduction
This exercise is designed to mimic what occurs to identify an unknown bacterium that is infecting a
patient. Clinical microbiologists receive patient samples every day in the lab. They are tasked to
identify the pathogen infecting patients. Thus, care must be used to properly identify the organism,
while maintaining strict BSL2, and at times BSL3, guidelines.
Upon receiving a patient’s sample, the patient’s information is logged into a computer. The
microbiologist then cultures the sample on various types of media that will support its isolation and
growth. For this, both rich and selective media are used. The microbiologist looks for individual bacterial
colonies present in the sample. Next, a Gram stain is performed to determine if the bacterium in
question is a 1. Generate a Dichotomous Key using the information provided in Table 11.1: Biochemical
Characteristics Of Gram Negative Bacteria. Later, you will use this information to
identify your unknown bacteria.
A dichotomous key is a tool that allows the user to determine the identity of items in the
natural world, such as trees, wildflowers, mammals, reptiles, rocks, and fish, etc. These
Keys consist of a series of choices that lead the user to the correct name of a given item.
“Dichotomous” means “divided into two parts”.
2. Referring to the biochemical properties of bacteria given in Table 11.1, create a Dichotomous
Key.
3. Biochemical test reactions are recorded as a ‘yes’ or ‘no’ (+ or -) result.
4. Once you complete your Dichotomous Key, you will have several branches of bacterial species
each ending at a unique species (name of the organism).
Biochemical Results to solve for Gram Negative ‘Unknown’ Bacteria
Introduction
This exercise is designed to mimic what occurs to identify an unknown bacterium that is infecting a
patient. Clinical microbiologists receive patient samples every day in the lab. They are tasked to
identify the pathogen infecting patients. Thus, care must be used to properly identify the organism,
while maintaining strict BSL2, and at times BSL3, guidelines.
Upon receiving a patient’s sample, the patient’s information is logged into a computer. The
microbiologist then cultures the sample on various types of media that will support its isolation and
growth. For this, both rich and selective media are used. The microbiologist looks for individual bacterial
colonies present in the sample. Next, a Gram stain is performed to determine if the bacterium in
question is a 1. Generate a Dichotomous Key using the information provided in Table 11.1: Biochemical
Characteristics Of Gram Negative Bacteria. Later, you will use this information to
identify your unknown bacteria.
A dichotomous key is a tool that allows the user to determine the identity of items in the
natural world, such as trees, wildflowers, mammals, reptiles, rocks, and fish, etc. These
Keys consist of a series of choices that lead the user to the correct name of a given item.
“Dichotomous” means “divided into two parts”.
2. Referring to the biochemical properties of bacteria given in Table 11.1, create a Dichotomous
Key.
3. Biochemical test reactions are recorded as a ‘yes’ or ‘no’ (+ or -) result.
4. Once you complete your Dichotomous Key, you will have several branches of bacterial species
each ending at a unique species (name of the organism).
5. You will then use this Dichotomous Key to solve for your ‘unknown’ bacteria (identify its Genus
and species name) based on the test done on your assigned organism using API 20e strips. You
will then complete the lab report of this exercise and submit it in Canvas for a grade.
Protocol: Day 1 Make your Dichotomous Key using the information provided in
Table 11.1: Gram-Positive Bacteria Biochemical Test Results.
and species name) based on the test done on your assigned organism using API 20e strips. You
will then complete the lab report of this exercise and submit it in Canvas for a grade.
Protocol: Day 1 Make your Dichotomous Key using the information provided in
Table 11.1: Gram-Positive Bacteria Biochemical Test Results.